251081 has 2 divisors, whose sum is σ = 251082. Its totient is φ = 251080.

The previous prime is 251071. The next prime is 251087. The reversal of 251081 is 180152.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 241081 + 10000 = 491^2 + 100^2 .

It is a cyclic number.

It is not a de Polignac number, because 251081 - 2¹⁰ = 250057 is a prime.

It is a super-2 number, since 2×251081² = 126083337122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (251087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125540 + 125541.

It is an arithmetic number, because the mean of its divisors is an integer number (125541).

2²⁵¹⁰⁸¹ is an apocalyptic number.

It is an amenable number.

251081 is a deficient number, since it is larger than the sum of its proper divisors (1).

251081 is an equidigital number, since it uses as much as digits as its factorization.

251081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 80, while the sum is 17.

The square root of 251081 is about 501.0798339586. The cubic root of 251081 is about 63.0867202479.

Subtracting from 251081 its product of nonzero digits (80), we obtain a square (251001 = 501²).

The spelling of 251081 in words is "two hundred fifty-one thousand, eighty-one".